In an effort to prevent or inhibit corrosion on metal sheet or strip, or to condition it for further processing, it is common practice to deposit a film of corrosion-preventative medium or lubricant on the strip. Processing of sheet and roll material through the use of rotary means such as roll stands is well known and commonly employed. One function of such roll stands is to apply and regulate the amount of a medium such as lubrication oil on material being processed. The material such as steel is typically initially wound in a coil and during further processing the coil is unwound as a strip and passed between the mill rolls. Depending upon the amount and consistency of the lubricant medium on the material, as well as the amount desired, the roll stand functions to regulate the amount by adding medium to the strip material, removing medium from the strip or both.
In order to maintain the desired amount of medium on the strip, a very precise pressure must be maintained between the rolls. In order that the layer of lubricant medium be uniform, the pressure between the rolls must be consistent across the length of the rolls. Further, in order that the strip or sheet properly tracks as it passes between the rolls, the rolls must be properly maintained in parallel alignment.
The deposit of the medium such as lubricants has been accomplished by various methods such as spray, electrostatic application, and direct application using both stationary and rotary means. Direct rotary application is presently being used in conjunction with spray application by first spraying the medium lubricant either directly on the strip or on the applicator rolls, then passing the strip between two opposed applicator rolls which distribute the compound evenly across the width of the strip.
Efforts to achieve uniform coating of the medium on the strip and avoid buildup of the medium have included the use of different materials and different surface configurations or textures. Different materials tried have progressed from rubber, to nylon, to urethane and more recently to composite "non-woven" rolls comprising non-woven synthetic fiber discs that are stacked and/or bonded together with a tough, yet flexible binder resin.
The use of non-woven rolls in place of rubber, urethane or felt rolls in ringer, oiler, tension/bridle or support roll applications has been known for at least 10 years. Unlike dense, closed surface rollers such as those made of rubber or nylon, the non-woven rolls such as made by the use of 3M material for example in various sizes and materials offer a high percentage void volume that provides a degree of absorption which aids in squeegeeing and tension functions during the rolling process.
One of the problems associated with the use of the direct rotary method particularly on non-woven rolls has been "wet edges." This phenomenon takes the form of narrow bands of processing medium located along the longitudinal edges of the strip or sheet. They are attributable to the fact that when running heavy gauge strip material, the non-woven rolls do not close completely at the strip edges, and a small amount of processing medium pools in these gaps and is carried through them. The porous roll faces, which are normally pressed either against the strip or against one another to effectively wring medium out of the rolls, run with a small amount of "free surface" at these gaps, and are not "wrung out" as they would be elsewhere along the roll face. The medium builds up in these areas and forms annular bands on the porous roll faces. At the exit side of the roll bite, some of this medium ends up being redeposited on the strip. The edge buildup can also create problems of splattering, misting, etc.
The present invention is provided to solve these and other problems.